If you are using DVI/HDMI, double check both ends of your source are fully seated in the connector. If you are using Component video (RGB cables) make sure all 3 are seated correctly in all 3 jacks. If this does not solve the problem, try a separate input. If this is still the issue, it's either your source ( Cable box, satellite, ps3, xbox, whatever), or the input board on the TV. Try basic troubleshooting first!